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How to get unix client to use higher speed NIC in its socket?

In multi-homed UNIX box, for servers, we can bind a specific IP address (or all of them) and ports to the socket. In sample client code, I just see the client socket associated with the server's IP address and port. I would like this client to connect to a server using only the client's higher speed card's IP address. Does anyone have some IPv4 sample client code to do this showing both the server and client socket association in the client code? (I am dealing with straight IP addresses, so DNS is not part of this topic.) My understanding is that without this binding, the client will use "lan0" (100 Mbps) instead of "lan1" (1Gbps).
Thanks,
Paul

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woolmilkporc

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mccarl

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phoffric

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"route" did work on my platform, but did on another. I take it that you want to look at the routing table. I found netstat does it. Here is what I got:
# netstat -rnv
Routing tables
Dest/Netmask Gateway Flags Refs Interface Pmtu
127.0.0.1/255.255.255.255 127.0.0.1 UH 0 lo0 32808
19.140.131.67/255.255.255.255 19.140.131.67 UH 0 lan1 32808
19.140.131.32/255.255.255.255 19.140.131.32 UH 0 lan0 32808
19.140.128.0/255.255.252.0 19.140.131.67 U 2 lan1 1500
19.140.128.0/255.255.252.0 19.140.131.32 U 2 lan0 1500
127.0.0.0/255.0.0.0 127.0.0.1 U 0 lo0 32808
default/0.0.0.0 19.140.128.1 UG 0 lan1 1500

>> I believe the "metric" value should be able to affect how this happens.
Could you explain what you mean by the "metric" value? Thanks.

BTW, I am not using this platform as a server; but rather as a workstation. /etc/hosts has three entries: 127.0.0.1, 19.140.131.67, and 19.140.131.32. (But, on a reboot, the .67 and .32 end up with the platform's name, and I have to change .67 manually to have two distinct names.)

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Infinity08

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phoffric

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The unix version is hp-ux 11i v3 (aka hp-ux 11.31).

To clarify my comment that "route" did work on my platform, but did on another, what I saw on hp-ux was:

# route
usage: route [inet6] [ -n ] [ -f ] [ -p pmtu ] [ cmd [ net | host ] args ]

But, on a VM GNU/Linux, typing "route" shows the routing table.

Looking at the man pages on both platforms, I see that the GNU/Linux "route" has "show / manipulate the IP routing table"; whereas the hp-ux "route" omits the "show" part. That is why I used hp-ux "netstat" to show the routing table.

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mccarl

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phoffric

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OP>> I would like this client to connect to a server using only the client's higher speed card's IP address.

Thank you for your inputs. I think the first two posts are in agreement in that when making a connection, the decision as to which NIC to use is not within the control of the application. (I should have tagged this as hp-ux to avoid the confusion.)

>> your lan1 route is still higher in the order so I would have assumed that would be the route chosen.
Looking at the last line:
default/0.0.0.0 19.140.128.1 UG 0 lan1 1500
I am just guessing here.. This seems to suggest that lan1 (the higher speed NIC) is the interface to the gateway. Perhaps that is the answer to the sub-question alluded to - how to know which NIC is used when two can both reach the destination.

BTW - iproute2 does not appear to be in this hp-ux platform.

I will look into this further, and post any findings that I come up with.

Regards,
Paul